1. Field of the Invention
The present invention relates to grease for a slide bearing which is formed of a porous sintered alloy-made bushing having pores impregnated with lubricating oil.
2. Description of Related Art
Many of various machines, such as construction machines, civil engineering machines, carrying machines, jacking machines, machine tools, and automobiles, employ slide bearing assemblies each comprising a slide bearing and a shaft which is inserted in the slide bearing and is supported to be slidingly rotatable in the circumferential direction. For example, an excavation mechanism of a hydraulic excavator as a representative of construction machines has a boom coupled to an upper swing body installed on a track body, an arm coupled to a fore end of the boom, and a bucket coupled to a fore end of the arm. At each of articulated portions of the boom, the arm and the bucket, a slide bearing assembly is generally employed which includes a slide bearing for supporting a pivot shaft.
In that type of slide bearing assembly, a bearing is often formed of an oil-impregnated and sintered alloy-made bushing which is obtained by impregnating highly-viscous lubricating oil in a porous bushing made of an iron-base sintered alloy. The oil-impregnated and sintered alloy-made bushing operates such that the impregnated oil swells and reduces its own viscosity due to frictional heat generated when the shaft slides relative to the bushing, whereby the lubricating oil exudes to form a thin oil film on a sliding surface. Therefore, the oil-impregnated and sintered alloy-made bushing exhibits the superior self-lubricating function (see, e.g., Patent Document 1)    Patent Document 1: JP,A 8-105444